package io;
import java.util.regex.*;
import java.io.*;
import java.util.*;
public class DirList {
    public static void main(String[] args) {
        File path=new File(".");
        String[] list;
        if(args.length==0)
            list=path.list();
        else
            list=path.list(new DirFilter(args[0]));
        Arrays.sort(list,String.CASE_INSENSITIVE_ORDER);
        for(String dirItem: list){
            System.out.println(dirItem);
        }
    }
}
class DirFilter implements FilenameFilter{
    private Pattern pattern;

    public DirFilter(String regex) {
        this.pattern = Pattern.compile(regex);
    }

    @Override
    public boolean accept(File dir, String name) {
        return pattern.matcher(name).matches();
    }
}
